Preparation of mercaptans



Rate-riled Feb. 3, 1931 UNITED STATES PATENT orlncr.

GEBALD .L. WENDT, OF STATE COLLEGE, PENNSYLVANIA, ASSIGNOR TO STANDARDOIL COMPANY, OF WRITING, INDIANA, A CORPORATION 01 INDIANA PREPARATIONOF MERCAPTAN S Nollrawing. Original application filed July 16, 1924,Serial No, 726,879. Divided and this application.

filed November 12, 1925. Serial No. 68,729.

' The present invention relates to preparation of lower mercaptans andparticularly tothe preparation of solutions of lower mercaptans suitablefor use inthe removal of sulfur and sulfur compounds from hydrocarbonoil, especially the lighter oils, such as gasoline, naphtha, burningoils and the like,

as describecl in my application Serial No.

I 7 26,37 9, filed July '16, 1924, which has eventuated into PatentNumber 1,668,225 issued May 1, 1928, from which the present appl cationhas been divided.

The preferred lower mercaptan compounds, by which term I designate themercaptans (or,v soluble mercaptides thereof)- have less than 10'carbonatoms and boil below 350 F.

According to the present invention I treatsolution generally. containsappreciableamounts of lower sodium mercaptides. The sodium sulfide alsocontained therein is de-,. composed and precipitated as calcium sulfidewhich is removed from the solution of mercaptides by decantation orfiltration. This decompositionmay suitably be efiected with lime orcalcium hydrosulfide. In actual practice spent lime or lime solutionsthroughi which refinery gases have been passed, may

be used such spent lime being largely composed of calcium hydrosulfide.

As a specific example, two parts of spent caustic and three parts ofspent lime solutions are mixed together, the precipitate separated,yieldin a red supernatant. li uor mainly constituted by a solution ofsodium mercaptides. These proportions may be varied according to theproportion of spent lime required to precipitate the sulfides in thespent caustic solution.

'1' claim:

1. The method of preparing a solution of lower mercaptan compounds whichcomprises washing petroleum naphtha with a caustic soda solution andadding to the resulting solution a calcium-f compound which reacts withthesodium sulfide present to precipitate the sulfide radical.

2. The method of preparing a solutionof caustic'soda solution, and ad'11 thereto a solution of calcium hydrogen sul de derived from thewashing of hydrocarbon gases with a limesuspension.

3. The *method of preparing a solution of lower mercaptan compoundswhich comprises washing petroleum naphtha with a caustic soda solution,addingto the resulting solution. a calcium compound which'reacts; withthe sodium sulfide present .to precipitate the sulfide .radical, andseparating the precipitate-from the-solution.

4. The method of preparing a solution'of lower mercaptan compounds whichcomprises washing petroleum naphtha with a caustic sodasolution, addingthereto calcium hydrogen sulfide derived from the treatment ofhydrocarbon gases with lime, and remov ing precipitated calcium sulfidefrom the solution.

' GERALD L. WENDT.

